Building on seven years of previous research, scientists at the Israeli Weizmann Institute of Science have now grown a bottled mouse embryo – ex utero – to the extent of organ and organ development. This is the longest thing a mouse embryo has ever grown outside the uterus, and it could open the door to new opportunities to study how mammals develop – and what could go wrong through that process.
And not just mice.
“This sets the stage for other species,” Weizmann development biologist and team leader Jacob Hanna told MIT Technology Review. “I hope it will allow scientists to grow human embryos until week five.”
Mouse in Jar
Mouse embryos were grown in a jar for up to 11 to 12 days, hair over half of the mouse movement period.
To do this, the team developed a device – to be published in Nature – that includes rotating bottles. The bottles contain blood serum from human umbilical cords, according to a Technology Review, as well as pumped-in oxygen.
This gets the vital gas into the cells, which Hanna compared to a COVID-19 patient on an air conditioner, where it powers blood and organ systems.
Getting the air pressure and proper oxygen levels was the hardest part, Hanna told Science; “We learned how to control the ventilation system.”
Growing the mouse embryo ex utero it was a two-step process. Initially, the team had to remove the embryo from a pregnant mouse and grow it on a culture plate from day 5 to day 7 of pregnancy. That’s when the embryos go through gastrulation, going from an empty tennis ball of cells to a structure where specific cells are expected to form specific nappies.
Once they hit that point, the mouse embryos enter the rotating bottles, where they have grown all the way to developing hind legs, are the team reports in their Nature paper.
The mouse embryo dies longer than this point because it grows too large for the oxygen to be pumped in efficiently.
“It looks pretty amazing,” Alexander Meissner, a developmental biologist at the Max Planck Institute for Molecular Genetics that was not resolved by the study, told Science. “The fact that (the researchers) can culture these embryos and keep them alive for so long – is amazing.”
Knocking Open the biological black box
“Establishment of the mammary gland plan occurs shortly after the embryo is introduced into the mother’s uterus, and our understanding of developmental processes after implantation remains limited,” the researchers wrote. in their abstraction.
In other words: we can’t really see what happens, because it happens in the uterus. This major stage of development takes place in a biological black box, limiting what scientists can learn about mammalian development.
According to Popular Mechanics, the new system will allow researchers to study the impact of several variables on embryo development. Everything from genetic modification to tissue handling and alteration to the chemical environment may be possible.
Mouse embryos were grown in a jar for up to 11 to 12 days, hair over half of the mouse movement period.
The roll bottle system “opens new doors by making accessible embryos for detailed study of many aspects of their development,” CalTech development biologist Magdalena Zernicka-Goetz told Science, and “will greatly enhance to the field, which we certainly plan to take advantage of. ”
That system is still complex and expensive, and can be improved; growing the mouse embryo completely in the bottle, for example, would greatly simplify the process.
Seeing deeper into embryo development may not help researchers understand exactly what is going on in the process, but also when and where it will go. wrong.
When mouse embryo research is considered along with new work examining blastoids (lumps of engineered cells that can be reported embryos) the “two milestones could come together to unravel the mysteries of very early pregnancy , with the least possible ethical quagmires, “Popular Mechanics’ Caroline Delbert writes.
Past the Mouse Embryo
These quagmires are ethical no trivial. Hanna is clear about the research opening up the opportunity to study human embryos up to week five of their gestation.
Already the ethical influences have come into play. Going so far into the first trimester research can be close to contraception, and the ethical, moral and social influences that make it the third rail.
Growing a mouse embryo for eleven days in a rotating jar does not mean that ex utero human embryo is just late, it is a proof of concept.
“I understand the difficulties. I understand. You’re entering the realm of genitals,” Hanna told MIT Technology Review.
Researchers may be able to understand not only what exactly is going on in the process, but also when and where it will go wrong.
He says, however, that researchers are already studying human embryos up to five days old in IVF clinics, which are often destroyed in the process.
“We need to see human embryos gastrulate and form organs and start to infect it. The benefit of growing human embryos to week three, week four, week five is very helpful,” he said. Hanna. “I think these tests should be considered anyway. If we can get to a progressive human embryo, we can learn so much.”
Looking into the development process could reveal why so many embryos are failing in the uterus, Delbert notes – something crucial for IVF patients
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